Refrigeration systems are conventionally known for cooling the interior of a cold storage, such as a chiller or a freezer.
For example, Patent Document 1 discloses a refrigeration system for cooling the interior of a cold storage in a container for use in sea transport or other transports. This refrigeration system includes a refrigerant circuit in which a compressor, a condenser, an expansion valve and a cooling heat exchanger (an evaporator) are connected. The refrigerant circuit in the refrigeration system operates in a vapor compression refrigeration cycle by circulating refrigerant therethrough. Thus, the refrigerant flowing through the cooling heat exchanger takes heat from air in the cold storage to evaporate and thereby cool the air in the cold storage. The refrigeration system is capable of a freezing operation for freezing stored goods in the container by cooling the air in the cold storage with temperatures below zero degrees Celsius and a chilling operation for chilling stored goods in the container by cooling the air in the cold storage with temperatures above zero degrees Celsius.    Patent Document 1: Published Japanese Patent Application No. 2002-327964